Electro hydraulic servo device



Feb. 26, 1963 M. P. woLPlN ETAL 3,078,863

ELECTRO HYDRAULIC sERvo DEvIcE Filed April 12, 1957 INVENTORS MARTIN P.WOLPIN JOHANNES G. GOERNER BY @244g M M4 TTH/VEYS 3,078,863 PatentedFeb. 26, 1963 ,3,678,863 ELECTRO yHYDRAULIC SERV() DEVICE Martin P.Wolpin, Tonawanda, and Johannes G.Goer

ner, Snyder, N.Y., assignors, by mesne assignments, to

Bell Aerospace Corporation, Wheattield, N.Y., a co1'- pnration ofDelaware Filed Apr. 12, 1957, Ser. No. 652,608 -2Claims. v(Cl. 137-82)This invention relates in generalto servo mechanisms, and-in 'particularto electro hydraulic servo valves, such as shown in copendingapplication, Serial No. 511,088 tiled May V25,- 1955, by MartinP.Wolpin,fet al. Furthermore, this invention comprises improvements overmechanisms as shown for example in U.S. Patents 2,655,939; 2,655,940;2,625,136; 2,767,689; Vand British Patent 712,329'of 1954.

An object lof the present invention is to provide `a valve of theaforesaid vtype in which the electrical parts of the valve are sealed otin improved manner from the fluid containing chambers thereof.

Another object is to provide `an improved valve as aforesaid wherein thearmature is mounted and stabilized in its fulcruming operation inimproved manner.

Another object is to provide an improved device as aforesaid wherein thearmature element is stabilized against acceleration forces.

Another object of the invention is to provide an improvide valve asaforesaid which may be economically made by standard type productionmethods.

Another object is to provide a valve as aforesaid having relatively fewparts.

Other objects and advantages of the invention will be apparent from thefollowing specification wherein one form of the invention is shown inthe accompanying drawings, of which:

FIG. l is a vertical sectional view, somewhat in diagram, of one form ofthe device of the invention; and

FIG. 2 is a sectional view taken on line II--II of FIG. 1.

As shown in the drawing, one form of the device of the invention may beemployed in conjunction with an hydraulic valve mechanism shown tocomprise a body having therewithin a valve spool 25 and oil passageways(not shown) as disclosed for example in FIG. l of copending U.S. patentapplication Serial No. 511,088 tiled May 25, 1955, by Martin P. Wolpinet al.; the fluid passageways exiting from the Valve body 15 asindicated at 16, 18, 20, 22, 30, 32 and 34. As in the prior applicationreferred to, an actuator comprising cylinder 24, piston 26, andconnecting rod 28, or the like, may be operatively coupled to the fluidconduits 20, 22 so that the latter open into the cylinder 24 at oppositesides of the piston. The port 16 constitutes the pressured fluid inletof the valve mechanism, while the port 18 constitutes the return line;and thus it will be understood that shifting of the valve spool 25within the body 15, as controlled by the electroc-magnetic component ofthe device as will be explained hereinafter, will cause the actuator 2Sto be displaced in accord with the purpose of the mechanism.

As in the case of the copending patent application, the fluidpassageways 30, 32 normally supply oil under equal pressures fromchambers at opposite ends of the valve spool 25, to correspondingopposed nozzles 40, 42 mounted as in a body block 44 and arranged to jetoil against opposite sides of a flattened end portion 46 of the armatureS0 of the electromagnetic component of the device. The armature endportion 46 is disposed within an oil chamber 52 formed in body block 44,and chamber 5.2 communicates with port 34 which leads to the oil returnconduit 13. The

armatureend-portion46-is normally centered between the nozzles 4t), 42and isslightly spaced equally inv relation therefrom'whereby constantows ofoil may pass through the-nozzles4tl,-4`2 from the chambersl atopposite ends of the'valve spool against thev armaturel part 46 andthence throughthe return conduit. However, any displacement of thearmature part relative to the -noz'zles 40, 42 will differentiallythrottle the latter, and thereby upset the previous pressure equilibriumat opposite ends of the valve spool '25. This will cause the valve spoolto shift with consequent adjustment of thevalve action controlling iiowof oil from the inlet 16 throughactuator parts 20, 22; therebyenergizing the actuator 28 consonant with the degree of detiection ofthe armature part 46 from -its normalcentralized position.

To provide Yfor such operation of the armature it is resiliently'mountedrelative to the body portions'44, 54; as shown inFlG. l such resilientmounting may beV providediby means of a hat-shaped housing 56'forme`d ofspring material mounted in liuid sealed relation to and embracingthemidportion of the armature bar 50; the bottom skirt portion of thehousing 5.6 being welded or other-wiselsuitably fixed in fluid-sealedrelation as indicated at 53 to a base plate 66 which is bolted asindicated at 62 to the body block 44. Thus, the joints between thehousing 56 and the armature 50 and the base plate 60 are ofiluid-pressure-sealed type, and a pressure seal as indicated at 64 ispreferably employed to seal the joint between the plate 60 and the bodymember 44. As shown in FIG. 1, the armature device is convenientlyconstructed of an upper section 50 and a lower section 65 carrying thellat end portion 46; the sections 50, 65 being telescopically intertttedto provide the unitary assembly.

To cause the armature to rock upon the housing 56 as its fulcrum,electro-magnet coils 68, are mounted within an enclosing housing 72 atopposite sides of the armature, and are arranged to be differentiallyenergized in response to any control or error or other input signal, asis well understood in the art. Permanent magnets as indicated at 74, 76may also be employed at opposite sides of the armature for normallybiasing the armature to centralized position. Thus, rocking of thearmature for differential throttling of the nozzles 40, 42 will beaccomplished in response to a signal and to a degree commensurate withthe strength of the signal to the coils 68, 70, as they may overcome thebalanced forces of the permanent magnets and as controlled by the springrate of the resilient housing 56. Thus, the housing 56 functionssimultaneously to normally spring-bias the armature towardsnozzle-centered position and controls oscillations thereof and returnsit to central position upon lapse of any biasing signal; while at thesame time it fluid seals the coils 68, 76 from contamination by oil fromthe nozzle chamber of the mechanism.

It is another particular feature of the present invention that the upperend of the support tube 56 is stabilized in a novel manner, such as bystraps Sii-S0 extending diametrically from the upper end of the tube 56into fixed connections with opposite sides of the base member 82 whichmay be either integral with the base member 44 or rigidly connectedthereto to assist in mounting the components of the mechanism. Thestraps 80-86 extend in the plane of oscillation of the armature 50i-65,and thus they lirmly maintain the center of oscillation of the armaturealways at the same elevation; that is, in line with the straps 862-66.Hence, in spite of varying net magnetic and hydraulic forces on thearmature, the armature always pivots about the same center; and thus itis practicable to construct the device to accept lateral forces withuniformly predictable results. None the less, because the straps 80--86are flexible they provide no interference with oscillation of thearmature.

What is claimed is:

1. A pilot valve for control of a pair of oppositely arranged fluidpressure nozzles, said valve comprising a body, a resilient collarcarried by said body in uid-sealed relation therewith, a llapper valveassembly comprising an armature extending through and carried by saidcollar in fluid-sealed relation therewith and formed with a tip portiondisposed between said nozzles for oscillating movement relative thereto,restraint means extending from said body to said collar to stabilize thelatter against lateral displacement and thereby maintain a xed level offulcruming of said armature relative to said body, and motor meansoperable to impose biasing forces upon said armature whereby operationof said motor means will cause the dapper valve assembly to rock whileelastically deforming said collar.

2. A pilot valve for control of a servo valve comprising a body,oppositely arranged tluid pressure nozzles carried by said body, aresilient collar carried by said body in duid-sealed relation therewithadjacent one end of said collar, an armature assembly formed ofmagnetio-responsive material extending through and carried by theopposite end of said collar in duid-sealed relation therewith and formedwith a flat tip portion disposed between said nozzles for oscillatingmovement relative thereto, flexible strap means extending from said bodyin the plane of oscillation of said armature and connected to saidcollar at a point spaced from said one end thereof to stabilize aportion thereof against lateral displacement and to thereby establish afixed level of fulcruming of said armature relative to said body, saidarmature extending outwardly from said collar and disposed between thepoles of an electromagnet, whereby variable signals received by saidelectromagnet will cause the armature assembly to rock within saidcollar for corresponding variable throttling of said nozzles.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Control Engineering, McGraw-Hill Publication, N.Y.C., May1955, page 21, Moog Advertisement.

1. A PILOT VALVE FOR CONTROL OF A PAIR OF OPPOSITELY ARRANGED FLUIDPRESSURE NOZZLES, SAID VALVE COMPRISING A BODY, A RESILIENT COLLARCARRIED BY SAID BODY IN FLUID-SEALED RELATION THEREWITH, A FLAPPER VALVEASSEMBLY COMPRISING AN ARMATURE EXTENDING THROUGH AND CARRIED BY SAIDCOLLAR IN FLUID-SEALED RELATION THEREWITH AND FORMED WITH A TIP PORTIONDISPOSED BETWEEN SAID NOZZLES FOR OSCILLATING MOVEMENT RELATIVE THERETO,RESTRAINT MEANS EXTENDING FROM SAID